The present invention relates to a self monitoring device for attachment to the body, which incorporates real-time measurement of body movement and physiological analytes of metabolism (e.g. glucose) that can be modulated by physical activity. The device algorithm enables real time and personalised modulation of the selected physiological analyte(s) through cued activities and other evidence based clinical guidance dependent on previous and current analyte levels and previous and current patterns of movement.
The invention is particularly, but not solely, concerned with simple practical procedures that can readily be conducted by unskilled persons diagnosed with Type 2 Diabetes (T2DM) to provide reliable guidance on engagement in physical activity to regulate blood glucose levels and minimise the period of time spent in a hyperglycaemic state. The invention is also concerned with the independent and secure communication of body movement and physiological analyte levels together with evidence based clinical management information to skilled professionals within the person's clinical care team to assist in the management of the condition.
An important objective of the device is to enable persons with T2DM, supported by their clinical care team, to recognise the contribution that specific patterns of physical activity can have on glucose control and the reduction of time spent in hyperglycaemia and to guide sustained incorporation of these patterns of activity into everyday life to reduce long term risks of complications and cardiovascular disease arising from T2DM.
Many high quality studies have demonstrated the importance of sustained engagement in even low intensity physical activity to regulate physiological glucose levels and reduce the time spent in hyperglycaemia (e.g. “Continuous low- to moderate exercise training is as effective as moderate- to high-intensity exercise training at lowering HbA1c in obese T2DM patients” Hansen et al, Diabetologia 2009 52 1789-1797).
A recent position statement by American College of Sports Medicine and the American Diabetes Association (Med Sci Sports Exerc. 2010 December; 42(12):2282-303) summarises the current evidence bases and recommendations stating:
“Although physical activity (PA) is a key element in the prevention and management of type 2 diabetes mellitus (T2DM), many with this chronic disease do not become or remain regularly active. High-quality studies establishing the importance of exercise and fitness in diabetes were lacking until recently, but it is now well established that participation in regular PA improves blood glucose control and can prevent or delay T2DM, along with positively affecting lipids, blood pressure, cardiovascular events, mortality, and quality of life. Structured interventions combining PA and modest weight loss have been shown to lower T2DM risk by up to 58% in high-risk populations. Most benefits of PA on diabetes management are realized through acute and chronic improvements in insulin action, accomplished with both aerobic and resistance training”.
The report discusses the benefits of physical training, along with recommendations for varying activities, PA-associated blood glucose management, diabetes prevention, gestational diabetes, and safe and effective practices for PA with diabetes-related complications.
Commercial technology for the continuous monitoring of blood glucose has been available for some ten years. The Abbott freestyle navigator is well validated and is employed by clinics for continuous blood glucose monitoring of patients with diabetes (http://www.freestylenavigator.com/index.htm).
A primary objective for such systems has been to improve glucose and insulin management in Type I diabetes (T1DM) (Reducing glycaemic variability in type 1 diabetes self-management with a continuous glucose monitoring system based on wired enzyme technology. Danne T et al. Diabetologia. 2009 August; 52(8):1496-503. Epub 2009 Jun. 13), development of closed loop insulin injection (artificial pancreas) systems (e.g. J Diabetes Sci Technol. 2009 Sep. 1; 3(5):1014-21, Closed-loop artificial pancreas using subcutaneous glucose sensing and insulin delivery and a model predictive control algorithm: preliminary studies in Padova and Montpellier. Bruttomesso D et al).
Avoidance of hypoglycaemia, especially nocturnally in T1DM, through the use of alarms associated with the measures glucose level has been a major objective (e.g. Diabetes Care. 2010 May; 33(5):1013-7. Epub 2010 Mar. 3. Prevention of nocturnal hypoglycemia using predictive alarm algorithms and insulin pump suspension. Buckingham B et al).
A recent review of clinical use of real-time continuous glucose monitoring (Curr Diabetes Rev. 2008 August; 4(3):218-22 by Battelino T & Bolinder J) reasonably summarises the current clinical perspective for the use of available technologies:
“Maintaining near-normal glycaemia in all patients with diabetes mellitus (DM) has become a standard and a well accepted recommendation. Unfortunately, most people with DM do not achieve this clinical goal because of marked glycaemic fluctuations and hypoglycaemia. Real-time continuous glucose monitoring (RT-CGM) has been introduced recently into clinical practice offering more knowledge about current glucose concentration and trend and enabling people with DM to intervene and prevent unwanted glucose excursions by acting upon real-time and predictive alarms. Several RT-CGM devices proved to be sufficiently accurate and feasible for routine use. Observational reports with The Guardian and Paradigm RT by Medtronic, the STS by DexCom, FreeStyle Navigator by Abbott and GlucoDay by Menarini established initial clinical benefit. Five randomised controlled trials (RCT) demonstrated significantly improved glucose variability or metabolic control, one of them showing a statistically significant and clinically meaningful decrease of HbA1c with a 3 months use of the Guardian RT (Medtronic, Northridge, Calif.)”.
And concludes:
“The great potential of RT-CGM devices to improve daily glucose control and quality of life in people with DM can only be developed further through RCTs, clarifying in more details the optimal clinical use and the most beneficial indications for this novel technique”.
Commercial technology for continuous monitoring of physical activity has been available for decades. The Sensewear system is a recently developed system reflecting the current state of the art and employs embedded MEMS accelerometers together with other sensors to measure body movement, temperature and skin conductivity on the upper arm to estimate measures of physical activity and energy expenditure (e.g. Br J Sports Med. 2010 July; 44(9):657-64. Epub 2008 Jul. 15. Validity of physical activity monitors in adults participating in free-living activities. Berntsen S et al) and such devices are increasingly employed in clinical studies requiring continuous monitoring of physical activity in free living persons (http://sensewear.bodymedia.com).
Pedometers and accelerometers have been widely used to promote increased engagement in physical activity for many decades and are increasingly integrated into web/mobile based systems to deliver lifestyle change programmes to improve health and wellbeing (e.g. J Med Internet Res. 2007 Apr. 27; 9(2):e7. Using internet and mobile phone technology to deliver an automated physical activity program: randomized controlled trial. Hurling R, Catt, M, Boni M D, Fairley B W, Hurst T, Murray P, Richardson A, Sodhi J S).
Accelerometer based devices have been employed in studies directed at improving glucose management in T2Dm. A recent pilot study (Diabetes Technol Ther. 2009 February; 11(2):113-8. The use of an Energy Monitor in the management of diabetes: a pilot study. Voon R, Celler B G, Lovell N H).
In this small study, five people with diabetes were given a triaxial accelerometer-based energy monitor that measured energy levels associated with activities of daily living. Participants wore the device for 3 months and continued their usual diabetes therapy. Glycosylated hemoglobin (HbA(1c)) was recorded to assess improvement in blood glucose control. The authors observed a a significant reduction of HbA(1c) from 7.48+/−1.21% to 6.98+/−1.44% (P<0.05) and that individuals engaged in physical activity at higher energy levels recorded much lower fluctuations in blood glucose level change between meals compared to those engaged in low physical activity levels. The study was also indicated promising results with respect to continued engagement with the weekly mean activity score showing an increase in activity levels from the second week to the final week.
The authors conclude:
“This pilot study demonstrated that the Energy Monitor could improve the management of diabetes by allowing people with diabetes to view and manage daily physical activity in addition to their usual diabetes therapy”
The combined use of continuous blood glucose and physical activity monitoring to motivate individuals with T2DM to engage in regular physical activity has been reported (J Clin Nurs. 2009 February; 18(3):373-83. Feasibility and acceptability of continuous glucose monitoring and accelerometer technology in exercising individuals with type 2 diabetes. Allen N A, Jacelon C S, Chipkin S R). The author's stated aim in this study was to develop role model data for a future intervention designed to motivate non-exercising individuals with type 2 diabetes mellitus to engage in regular physical activity. To explore this, the study described continuous glucose monitoring data and generated role model CGMS graphs and subsequently described a monitor to measure exercise amount and intensity to explore participants' experiences of the combined physical activity monitors and perceptions of the glucose monitoring data. The authors adopted a descriptive study design to describe physical activity patterns and glucose levels for 72 hours in nine exercising adults with type 2 diabetes. This was followed by a focus group interview to collect data from seven phase-1 participants. The authors analysed verbatim transcripts of the audio taped focus group for themes and trends. The authors describe how the glucose monitor data demonstrated lower glucose levels after exercise and how, compared to formal diabetes education, visual data from the glucose monitoring technology was perceived as more relevant to participants' particular, everyday experiences with respect to exercise, diet and stress. The authors state that participants reported a reinforced commitment to their exercise and diet regimens after using the continuous glucose monitoring system but also report technology issues such as discomfort when wearing activity monitors and issues relating calibration and event recording with the continuous glucose monitors.
The authors conclude: “Participants found that visual glucose monitoring data reinforced self-management behaviors, such as exercise. Our results suggest that data depicting the response of glucose levels to diet and exercise could be a useful tool to change behaviour in individuals with type 2 diabetes”.
In a separate study (Diabetes Technol Ther. 2009 March; 11(3):151-8. Continuous glucose monitoring in non-insulin-using individuals with type 2 diabetes: acceptability, feasibility, and teaching opportunities. Allen N A, Fain J A, Braun B, Chipkin S R). continuous glucose monitoring is employed to provide contextual data lifestyle intervention for non-insulin-using, sedentary individuals with type 2 diabetes mellitus (T2DM). The study investigated CGM in terms of feasibility and acceptability and dietary- and exercise-teaching events. This study did not consider delivery of real time feedback and demanded careful, independent record keeping of individuals for subsequent review with their clinical care team. About half the participants (52%) reported difficulty remembering to enter events into CGM monitors, but most (82%) kept an accurate paper log of events. Users also reported difficulty maintaining reference blood glucose measures to maintain calibration of the CGM. The majority of participants were willing to wear CGM again despite reporting minor discomfort at sensor site and with wearing the monitor. CGM data provided several teaching opportunities in non-insulin-using adults with T2DM and despite the issues experienced, the authors found CGM to be acceptable and feasible.
There is evidence that light to moderate physical activity and reduced sedentary time can improve glucose disposal (e.g. Diabetes Care. 2007 June; 30(6):1384-9. Epub 2007 May 1, Objectively measured light-intensity physical activity is independently associated with 2-h plasma glucose. Healy G N et al). In this study of 67 men and 106 women (mean age+/−SD 53.3+/−11.9 years) without diagnosed diabetes, but with impaired glucose tolerance, physical activity was measured by particpants wearing Actigraph accelerometers during waking hours for 7 consecutive days. Activity data was summarized as sedentary time (accelerometer counts/min <100; average hours/day), light-intensity (counts/min 100-1951), and moderate- to vigorous-intensity (counts/min > or =1,952). An oral glucose tolerance test was used to ascertain 2-h plasma glucose and fasting plasma glucose. The authors found sedentary time was positively associated with 2-h plasma glucose (b=0.29, 95% CI 0.11-0.48, P=0.002); light-intensity activity time (b=−0.25, −0.45 to −0.06, P=0.012) and moderate- to vigorous-intensity activity time (b=−1.07, −1.77 to −0.37, P=0.003) were negatively associated after adjustment for confounding factors. Light-intensity activity remained significantly associated with 2-h plasma glucose following further adjustment for moderate- to vigorous-intensity activity (b=−0.22, −0.42 to −0.03, P=0.023).
Although existing management of T2DM blood glucose is predominantly focused on dietary management, the linkage between physical activity and blood glucose control is now well established. Reductions in sedentary time and light to moderate activities (e.g. walking) have been shown to associate with improved glucose control. Existing approaches to engendering increased physical activity in T2DM through communication of blood glucose control rely on analysis of past patterns of blood glucose and physical activity to educate the patient to promote a continued mindfulness to engage in increased physical activity. None of these have combined real-time monitoring of blood glucose (or other metabolites or analytes) levels with monitoring of movement or activity to correlate the two and to provide direct input to the patient as to how their activity can modulate their blood glucose levels.